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  • 03. Hydrosphere::03.01. General::03.01.05. Operational oceanography  (1)
  • super-ensemble, surface drift forecast  (1)
  • wave breaking  (1)
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  • 1
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    Investigating the impact of surface wave breaking on modeling the trajectories of drifters in the northern Adriatic Sea during a wind-storm event (2012)
    Elsevier Inc NY Journals
    Details
    Publication Date: 2020-12-09
    Description: An accurate numerical prediction of the oceanic upper layer velocity is a demanding requirement for many applications at sea and is a function of several near-surface processes that need to be incorporated in a numerical model. Among them, we assess the effects of vertical resolution, different vertical mixing parameterization (the so-called Generic Length Scale –GLS– set of k–e, k–x, gen, and the Mellor–Yamada), and surface roughness values on turbulent kinetic energy (k) injection from breaking waves. First, we modified the GLS turbulence closure formulation in the Regional Ocean Modeling System (ROMS) to incorporate the surface flux of turbulent kinetic energy due to wave breaking. Then, we applied the model to idealized test cases, exploring the sensitivity to the above mentioned factors. Last, the model was applied to a realistic situation in the Adriatic Sea driven by numerical meteorological forcings and river discharges. In this case, numerical drifters were released during an intense episode of Bora winds that occurred in mid-February 2003, and their trajectories compared to the displacement of satellite- tracked drifters deployed during the ADRIA02-03 sea-truth campaign. Results indicted that the inclusion of the wave breaking process helps improve the accuracy of the numerical simulations, subject to an increase in the typical value of the surface roughness z0. Specifically, the best performance was obtained using aCH = 56,000 in the Charnok formula, the wave breaking parameterization activated, k–e as the turbulence closure model. With these options, the relative error with respect to the average distance of the drifter was about 25% (5.5 km/day). The most sensitive factors in the model were found to be the value of aCH enhanced with respect to a standard value, followed by the adoption of wave breaking parameterization and the particular turbulence closure model selected.
    Description: Published
    Description: 225-239
    Description: 3.7. Dinamica del clima e dell'oceano
    Description: JCR Journal
    Description: restricted
    Keywords: wave breaking ; turbulence ; drifter ; 03. Hydrosphere::03.03. Physical::03.03.01. Air/water/earth interactions
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
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    PAPER (OA)
  • 2
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    Sueper-Ensemble techniques: application to surface drift prediction during the DART06 and MREA07 campaigns (2010)
    Details
    Publication Date: 2021-11-08
    Description: The prediction of the drift of floating objects is an important task, with applications such as marine transport, pollutant dispersion, and search-and-rescue activities. But forecasting surface drift is also very challenging, because it depends in a complex way on various interacting factors such as the wind, the ocean surface current, and the wave field. Furthermore, although each of the cited factors can be fore- casted by deterministic models, the latter all suffer from limitations, resulting in imperfect predictions. In the present study, we try and predict the drift of buoys launched during the DART06 (Dynamics of the Adriatic sea in Real-Time 2006) and MREA07 (Maritime Rapid Environmental Assessment 2007) sea trials, using the so-called hyper-ensemble technique: different models are combined in order to minimize departure from independent observations during a training period; the ob- tained combination is then used in forecasting mode. We review and try out different hyper-ensemble techniques, going from simple ensemble mean to techniques based on data assimilation, which dynamically update the model’s weights in the combi- nation when new observations become available. We show that the latter methods alleviate the need of fixing the training length a priori, as older information is au- tomatically discarded, and hence they lead to better results. Moreover, they allow to determine a characteristic time during which the model weights are more or less stable, which allows to predict how long the obtained combination will be valid in forecasting mode.
    Description: Published
    Description: 149–167
    Description: 4A. Oceanografia e clima
    Description: JCR Journal
    Description: open
    Keywords: super-ensemble, surface drift forecast ; 03. Hydrosphere::03.01. General::03.01.05. Operational oceanography
    Repository Name: Istituto Nazionale di Geofisica e Vulcanologia (INGV)
    Type: article
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER (OA)
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